history+workplan: round-2 blueprint review; SHARD-WP-0006 hardening II

Records the round-2 critical review (history/260615-...-review-2) and
establishes SHARD-WP-0006 to: reconcile overview with hardened body (§A),
settle the journal/coordination-state model (event-sourced decision log;
single-vs-multi-writer concurrency — B-1+B-3), require an adapter conformance
suite (B-2), fix incremental-equivalence correctness + I-2 verification (B-4),
and track §C as O-8..O-11.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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# Critical review (round 2) — CoreArchitectureBlueprint.md (hardened)
Date: 2026-06-15 · Reviewer: tegwick (with Claude) · Subject:
`spec/CoreArchitectureBlueprint.md` after **SHARD-WP-0005** (commit f21b7b5) · Feeds:
**SHARD-WP-0006**
A second hostile pass over the *hardened* blueprint. Round 1 found design bugs; this round
finds (a) self-consistency regressions the surgical hardening introduced, and (b) deeper
second-order gaps — some of which the hardening *sharpened*. Verdict: the architecture is now
substantially sound; what remains in §B/§C are hard distributed-systems/operational questions,
not design smells — except §A (a real regression) and three foundational gaps in §B.
---
## A. Self-consistency regressions introduced by surgical hardening
The 9 edits deepened §6§9 but did not propagate to the **overview surfaces**, so the document
now contradicts itself between its summary and its body (and readers trust the summary).
- **A-1 (real contradiction).** §4 still says "Addressing, **equivalence**, and transclusion
key on identity" — the exact conflation T2 fixed in §7.2 (equivalence keys on *content
fingerprint across distinct identities*). → **WP-0006 T1**
- **A-2.** §4 "Projection — typed on two axes" and §4 "Provenance envelope … every artifact
carries [full wrapper]" are stale vs T7's §8.4 (two-axis = extension point; trivial default)
and §7.3 (layered effective-vs-own). → **T1**
- **A-3.** §10 policy surface omits knobs the hardening added (freshness/staleness §8.8,
squash-compaction §8.1, conflict-resolution preset §8.6, tenant-partition) — yet §11 defines
`policy/` as "owns the §10 surface." The module contract points at a stale list. → **T1**
- **A-4 (cosmetic).** §3 diagram + §11 header still say "L4 rebuildable cache" / "15 spectra,"
advertising the pre-hardening model (§8.7 incremental-first; §6.5 orthogonal-core). → **T1**
Meta-point: surgical editing hardened the body but regressed whole-document coherence; v2
needs an **overview-reconciliation pass**.
## B. Foundational gaps (serious; some sharpened by the hardening)
- **B-1 — The journal is now a concurrent-write DB, but it's single-writer Git.** §8.6's
consistency model assumes "the journal is local Git, read-your-writes." L4 multi-tenant + the
L6 Orchestrator API imply a server; HA/scale implies *multiple* instances. Concurrent commits
of coordination-canonical state to one git journal = lock contention / merge races; Git is not
a concurrent-write store. Either single-writer-per-space (an unstated HA ceiling) or a real
concurrent coordination store with Git as an *export*. **T1 of WP-0005 worsened this** by
loading more canonical state into the journal. The keystone unanswered question. → **T2**
- **B-2 — Capability-as-data trusts self-reported profiles with no conformance check.** I-3 +
§6.5's degradation contract assume the profile tells the truth. A buggy adapter (claims
`merge=git/text`, corrupts; claims `notify`, never emits) silently poisons every degradation
decision. No **adapter conformance suite** (declared profile == observed behavior) exists.
Foundational for an architecture whose correctness rests on profile accuracy. → **T3**
- **B-3 — "Coordination-canonical state in the journal" has no representation design.** T1
relocated overlays/bindings/aliases/equivalence-sets/merges into "the journal" without saying
*how* Git stores structured mutable state. "All equivalences touching X" over a git-of-files
is O(scan) unless indexed — and an index is L4/derived. The new central concept is a black
box; resolve *with* B-1. → **T2**
- **B-4 — Incremental equivalence is under-specified/likely incorrect; I-2 only eventually
true.** §8.7 re-verifies a changed page's *new* candidate set but not the pairs it *leaves*
(a page exiting an LSH bucket can break an existing equivalence edge); the delta is not
additive. Deeper: incremental maintenance drifts from `f(canonical)`, so I-2 holds only
eventually, guaranteed solely by an expensive reconcile-against-rebuild. Needs a stated
verification mechanism (background checker / digest-vs-sampled-rebuild). → **T4**
## C. Real but second-tier (track as open problems O-8…O-11)
- **C-1 — Mechanism-over-policy → operator burden; no preset bundles.** ~7 knob families with
sub-modes and interactions; only authz (L0L4) bundles into personas. Need named bundles
("personal vault" / "team wiki" / "enterprise federation"). → **O-8 / T5**
- **C-2 — Tenant partitioning (I-13) vs shard sharing + lazy projection.** A shard in two roots
is cached twice → duplicate storage + double refresh on rate-limited backends. Shard
exclusive-to-one-root or shareable? Unresolved. → **O-9 / T5**
- **C-3 — Span-level authz + transclusion is an unmodeled leak path.** Authz is per
page/shard/tenant; transclusion crosses shards at span granularity → a page can leak a span
past its ACL (aggregation/inference). §7.3's ⊕ also stops being simple two-level inheritance
across a transclusion boundary. → **O-10 / T5**
- **C-4 — Union-under-unavailability undefined.** Freshness covers *stale*, nothing covers
*down*. The dead-shard read path (partial union? error? last-known?) is unspecified though
it's the commonest real failure. → **O-11 / T5**
## D. Recommended resolution (→ SHARD-WP-0006)
1. **§A reconciliation** (T1) — make the overview match the hardened body.
2. **Journal & coordination-state model** (T2) — settle single-vs-multi-writer and separate the
**coordination-state store** from the **content-history journal**. Likely resolution:
**event-sourced coordination** — an append-only *decision log* is the coordination-canonical
tier (git-addressable, I-6 preserved); the queryable current state (alias table, equivalence
set) is a *derived fold* of the log (disposable). Append-logs tolerate concurrency far better
than mutable-file Git; state a concurrency model. Resolves **B-1 + B-3** together.
3. **Adapter conformance suite** (T3) — make a passing conformance run part of the contract
(B-2): every adapter proves declared profile == observed behavior.
4. **Incremental correctness + I-2 verification** (T4) — fix the leaving-bucket re-verification
and propagation; add a background consistency-checker / derived-tier digest so I-2 is
verifiable, not merely asserted (B-4).
5. **Track §C** (T5) — O-8…O-11 with chosen direction + revisit trigger; close-out.

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@@ -14,4 +14,5 @@ design evolution.
| Date | Record | Subject |
|------|--------|---------|
| 2026-06-15 | `260615-core-architecture-blueprint-review.md` | Critical review of `spec/CoreArchitectureBlueprint.md` (commit 9b5b393); inputs to `SHARD-WP-0005` |
| 2026-06-15 | `260615-core-architecture-blueprint-review.md` | Critical review of `spec/CoreArchitectureBlueprint.md` (commit 9b5b393); inputs to `SHARD-WP-0005` |
| 2026-06-15 | `260615-core-architecture-blueprint-review-2.md` | Round-2 review of the hardened blueprint (post-`SHARD-WP-0005`, f21b7b5); inputs to `SHARD-WP-0006` |

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---
id: SHARD-WP-0006
type: workplan
title: "core architecture hardening II (round-2 review fixes)"
domain: whynot
repo: shard-wiki
status: active
owner: tegwick
topic_slug: whynot
created: "2026-06-15"
updated: "2026-06-15"
depends_on:
- SHARD-WP-0005
---
# SHARD-WP-0006 — Core architecture hardening II
## Goal
Resolve the round-2 review (`history/260615-core-architecture-blueprint-review-2.md`):
reconcile the document's overview with its hardened body (§A), settle the three foundational
gaps (§B: journal concurrency + coordination-state representation; adapter conformance;
incremental-maintenance correctness + I-2 verification), and track the second-tier items
(§C) as open problems. Deliverable: a revised `spec/CoreArchitectureBlueprint.md` that is
**self-consistent** and answers the keystone question — *single- vs multi-writer journal, and
where mutable coordination state actually lives*.
## Context
- Round-2 review: `history/260615-core-architecture-blueprint-review-2.md` (A-1…A-4, B-1…B-4,
C-1…C-4; resolution §D).
- Round-1 review + first hardening: `history/260615-core-architecture-blueprint-review.md`,
`SHARD-WP-0005`.
- Constraint to honour: INTENT I-6 / "Git-addressable coordination layer" — any coordination
store must remain git-addressable (history/patches/review/backup), not abandon Git.
**Non-goal:** Implement anything. Architecture spec revision only.
---
## §A overview-reconciliation pass
```task
id: SHARD-WP-0006-T1
status: todo
priority: high
```
Make the overview match the hardened body (review A-1…A-4):
- **A-1 (bug):** §4 "Page identity vs placement" — remove "equivalence … key on identity";
state equivalence keys on content fingerprint across identities (align with §7.2).
- **A-2:** §4 "Projection" → trivial-default + extension-point framing (align §8.4); §4
"Provenance envelope" → layered effective-vs-own (align §7.3).
- **A-3:** §10 policy surface — add the missing knobs (freshness/staleness mode, history
squash-compaction, conflict-resolution preset, tenant-partition); keep §11's `policy/`
pointer accurate.
- **A-4:** §3 diagram + §11 header — "incremental-maintained derived tier (rebuild = fallback)"
and "orthogonal-core capability profile," not "rebuildable cache / 15 spectra."
---
## Journal & coordination-state model (single vs multi-writer)
```task
id: SHARD-WP-0006-T2
status: todo
priority: high
```
Settle the keystone (review B-1 + B-3 together). Decide and document:
- **Separate the content-history journal from the live coordination state.** Proposed
resolution: **event-sourced coordination** — an append-only **decision log** (overlays,
bindings, aliases, merges as events) is the **coordination-canonical** tier and is
**git-addressable** (preserves I-6); the queryable *current* coordination state (effective
alias table, equivalence set) is a **derived fold** of the log (disposable, indexable, L4).
This resolves B-3 (representation = event log; queries = derived index) and refines the §1
three-state framing (coordination-canonical = the decision *log*, not a mutable file).
- **State the concurrency model (B-1).** How multiple orchestrator instances append safely:
serialized append per space (with the HA story made explicit) and/or
conflict-free ordering of independent appends; what "read-your-writes" means across
instances; where Git is authoritative vs a materialised export.
- Update §1 (refine coordination-canonical = decision log), §4 (Coordination journal /
Overlay), §8.1/§8.2, §8.6 (consistency now grounded on the log + a stated concurrency model),
§11 (a `coordination/` event-log store + derived-fold index).
---
## Adapter conformance suite (profiles must be verified, not asserted)
```task
id: SHARD-WP-0006-T3
status: todo
priority: high
```
Fix B-2. Make capability-as-data trustworthy: add to the adapter contract (§6) a
**conformance-suite requirement** — a published battery that, given a binding, verifies its
**declared capability profile matches observed behaviour** (each declared verb/position is
exercised; mismatches fail registration). State that an adapter is only admissible if it
passes; that the suite is versioned with the contract; and that profile claims are
**verified, never self-asserted** (this is what makes I-3 / §6.5 sound). Update §6.4/§6.5 and
add the conformance obligation to the acceptance posture.
---
## Incremental-maintenance correctness & I-2 verification
```task
id: SHARD-WP-0006-T4
status: todo
priority: medium
```
Fix B-4. In §8.7: correct the incremental equivalence algorithm — a changed page must
**re-verify the candidate pairs it leaves** (bucket exits) and **propagate** to pages whose
equivalence depended on it, not only its new candidates; the delta is not additive. Add an
**I-2 verification mechanism**: a background consistency-checker comparing a **digest of the
derived tier** against a sampled/periodic recompute, so `derived = f(canonical)` is *verified*,
not merely asserted; on mismatch, recompute the affected partition. State that I-2 is an
*eventually-verified* property with a named checker, and note the residual in §12.
---
## Track second-tier items; close-out
```task
id: SHARD-WP-0006-T5
status: todo
priority: medium
```
Add review §C as open problems in §12 (each with chosen direction + revisit trigger):
- **O-8** preset bundles ("personal vault" / "team wiki" / "enterprise federation") over the
§10 policy surface — direction: ship a small set of named personas; trigger: operators
mis-configuring interacting knobs.
- **O-9** shard sharing across roots vs tenant partition (I-13) — direction: shard exclusive to
one root by default, explicit shared-read binding otherwise; trigger: a shard legitimately
needed live in two tenants.
- **O-10** span-level authz under transclusion (aggregation/inference leak) + ⊕ composition
across transclusion boundaries — direction: a transcluded span inherits the *stricter* of
source and host authz; provenance ⊕ composes source-page-envelope under the host; trigger: a
cross-authz transclusion in practice.
- **O-11** union-under-shard-unavailability — direction: partial union + per-shard
"unavailable" provenance + last-known-projection where policy allows; trigger: SLA needs on
partial reads.
Refresh §14 decisions and §16 traceability (link this review + SHARD-WP-0006); refresh
invariants if any added. Final `check_repo_consistency` pass.
---
## Acceptance criteria
- Every round-2 finding A-1…A-4, B-1…B-4 is **resolved in the blueprint**; C-1…C-4 are tracked
as O-8…O-11 with a chosen direction (none silently dropped).
- The blueprint is **self-consistent**: overview (§1§5, §10) agrees with body (§6§9).
- The **journal/coordination-state model** answers single-vs-multi-writer and preserves I-6
(git-addressable coordination).
- The **adapter conformance** obligation makes capability-as-data (I-3) verified, not asserted.
- Each task committed; SCOPE/spec-README updated where status changes; state-hub synced.
## Suggested task order
T1 (reconcile, fast) → T2 (keystone journal/coordination model) → T3 (conformance) →
T4 (incremental correctness) → T5 (track §C + close-out).